Need vapor barrer in pole barn?

[Thumper & Buttercup]

A lot of the building company's can get the size insulation that a Morton building needs.

 

[Luremaker]

Here are a few pictures taken back in January 2004 when I was insulating my shop. In order to pass inspection the 6mil vapour barrier had to be sealed around all windows, electrical outlets, floor and on all seams. The inspector insisted on a well sealed barrier. I drywalled right over the vapour barrier. I usually heat my shop 5 days per week. Moisture has never been a problem with 3 or four of us working for 8 to 10 hours per day 5 days per week.

For the past few winters I used a pair of 4800 watt electric shop heaters and a little solar to bring the shop up to a comfy 68-70 degrees then ran a single heater as required. This year I installed a corn/pellet stove and have used an average 20 bushels per month to heat my shop. My shop is 40 x 60 x 14 and divided in two. The side I work in is approx 1600 sq ft, heated to around 70 and the other 800 sq ft stays between 58 and 62 degrees.

 

[sixdogs]

Luremaker--That is a fine looking shop and the photos very helpful. Thank you.
The reason I am not using Morton is the price. Now, I'm not a piker but they want more than double what the Amish want and I feel both will do an equally fine job. We are talking a $10,000 difference here.
I am not a tough sell and am willing to pay more for a better job that is locally done or by guys that need the work. I don't want the lowest price on a job. If i though Morton would do a better job I would use them.
But double the price for a simple task that doesn't require an unusual level of skill? That doesn't seem wise.

 

[PA hayseed]

the funny thing here is that the standard batt insulation will tell you to face the kraft side toward the living area. The kraft face is supposed to act like a vapor moisture barrier. Some places tell you to put plastic over that.

When I did my addition last year, the code officer in my neck of the woods said I had to use kraft face batts (or an unheard of amount of spray foam), but wanted no plastic barrier.

To further confuse you, I went to just about every website, DIY sites, gov sites, manufacturer's site and I will tell you that there is conflicting information on those sites.

When you figure out what works after the fact, start your website.

In my pole building I used rigid foam insulation panels and batt insulation. I haven't had any problems in 4 winters, but who knows what could be hiding behind those walls.

Good luck to you.

 

[PILOON]

When I built I left out vapor barrier on a 4 ft section of outer wall for temporary reasons.
Came Feb I could feel cold 'radiation' on that wall area so I peeled back the insulation to find that the outer 4 of the 6 inches was solid with ice!
Areas with vapor barrier were totally bone dry!

Vapor will always condense on the warm side of the vapor barrier and that is why you want furring strips over the barrier and under the wall finish.
Never on the outer side of the insulation as the wool will simply become a sponge and rot your studs. (and I have seen that happen, takes about 10 yrs for a stud to become black mushy sawdust!)
Have seen it so bad that wallboard would actually buckle!

 

[srs]

In order to pass inspection the 6mil vapour barrier had to be sealed around all windows, electrical outlets, floor and on all seams.

Luremaker, what kind of black SEALANT did you use with the plastic vapor barrier. I've tried a few sealants, pure silicone, caulk, Great Stuff spray foam and they don't seem to stick very well to the plastic. Thank you.

 

[Luremaker]

Luremaker, what kind of black SEALANT did you use with the plastic vapor barrier. I've tried a few sealants, pure silicone, caulk, Great Stuff spray foam and they don't seem to stick very well to the plastic. Thank you.

I used Tremco Acoustical Sealant. It comes in a caulking tube and is a very soft sealant. I cut away some drywall last summer to alter some wiring and the sealant was still soft and pliable.

Tremco Acoustical Sealant - Tremco Commercial Sealants & Weatherproofing

 

[srs]

I used Tremco Acoustical Sealant.

Thank you. I'll check it out.

 

[sixdogs]

Sixdogs, Have you contacted Morton to see what they say? Like I mentioned to you in an earlier post my salesman gave me a copies of their installation guide regarding insulation and they are very specific about using plastic as a vapor barrier. They specifically address sealing any and all holes in the plastic. Give your salesman or Morton headquarters a call and see what they say. Better to do that now then to be sorry later on. Let me know. Good luck!

I sent a PM to you.

 

[440roadrunner]

I'm not sure there is a perfect answer to this question. If the outside of the building is metal any moisture that forms inside due to heating will move through the wall and insulation and condense on cold metal- if the metal is in contact with the insulation the insulation will get wet. Probably the best way to avoid that is the have an airspace between the batts and the outside wall that is open at the top of the wall into the vented attic. The problem with metal is that the moisture can't escape as vapor to the outside, unlike other siding materials. Your post mentions inside metal walls-the metal is a vapor barrier unlike sheetrock/OSB which would allow vapor to pass through, and the question is should you add another one between the metal and the fiberglass. If you do add a plastic vapor barrier any moisture that gets past the metal will condense on the plastic and may be trapped against the metal, but at least won't get into the insulation and will likely be able to re-enter the room at some point when you are not heating it. The real key is probably ventilation in these types of scenarios, so any moisture that does form can get out.

This is an incredibly important statement. I used to maintain HVAC and have seen several situations where vapor was a problem in buldings. I'm no insulation expert, but once you see a building with a serious problem, one can usually figure the cause.

In this part of the country, commercial pole buildings typically are insulated "minimally" (more can be added) with a sort of packetized stuff like a great big pillow